The invention relates to a method and to its devices making it possible to measure the tension and/or travel speed of an insulating filament, fibre, thread or wire without any contact with the latter. This device has numerous applications in all fields where it is necessary to know the value of the tension or travel speed of an insulating filament. More specifically, the invention applies to the textile field and more specifically to the spinning of textile filaments.
There are various methods for determining the movement or transit speed of a filament. One of these methods consists of evaluating the linear speed of the filament on the basis of the radius of the grooved pulley serving as the filament guide and the number of revolutions per second carried out around said grooved pulley.
The main disadvantage of this method is that it introduces significant errors on the measurement when the grooved pulley is worn. Moreover, it does not make it possible to take account of possible slipping of the filament on said grooved pulley.
Another known method makes it possible to measure the tensions of a textile structure held taut on one site. Such a method consists of supplying an excitation sinusoidal signal on a circular textile surface and measuring the displacement response with the aid of a contactless sensor or transducer. A transfer function curve or spectral signature can then be deduced. This method is more specifically defined in the article entitled "Measure tensions within the cloth" by Jean-Yves Catherin, published in BUREAUX D'ETUDES, No. 76. However, this method only applies to woven structures.